Adaptive Cruise Control (ACC) systems that control the speed of a host-vehicle relative to other-vehicles proximate to the host-vehicle are known. However, instances of inadvertent disengagement of the ACC has been observed where an operator of the host-vehicle accidently and imperceptibly (to the operator) pressed the brake-pedal while trying to maintain his/her foot in a ‘ready’ position. This can lead to a situation where the operator is unpleasantly surprised when the headway gap between the host-vehicle an other-vehicle forward of the host-vehicle unexpectedly decreased because the ACC has been inadvertently disengaged.